thing is, you can make a discount code, but it would only be on your mark up. then you can set it to what you want. if your suggesting your 50% off, i assumed you decreased your prices to half off - or at least made it so the prices looked that way adjusting for the markup faa has. but the prices are full looking to me. i know i'm on the high side of pricing, and if your half off, you would be doubling my stuff.
the hard part about the code is - you can either say - $xxx off - of your total (which will remove your mark up). or tell them it's 50% off your mark up... however 50% off shows a sort of desperateness, that devalues the work - the worth of the work. like your going out of business. and lower prices don't attract people as much as the higher ones.
a reason you may not be selling as well as you should are your keywords -- you have over a dozen words that don't belong in there - weather, water, sky, atmosphere, etc those should be removed because they are spam. instead you should focus on the fact it's tea, it's for a ceremony maybe a holiday used in your country. you have to focus on who these are for, and the demographic you chose is a bit tight. so just making it on sale won't attract customers.
in looking - you used the same keywords for all the thing you sent and very few of those even have those terms.
and i know that for a fact because i've tried coupons a few times and didn't get any bites. you would get more people if you advertised off the forum.
also you have a few that aren't for sale at all. in fact i think only the stuff on the first page is for sale.
---Mike Savad